Fotjrth to paul kolisch



A Ti] 26 1927.

p I v F. ALDENDORFF ELECTROMECHANICALLY CONTROLLED TELEPHONE SYSTEM Filed Aug. 26. 1921 6 Sheets-Sheet 1 11a verdan- Alaenczorf 3 e J a 1,625,779 Aprll 1927' F. ALDENDORFF ELECTROMECHANICALLY CONTROLLED TELEPHONE SYSTEM Filed Au 26, 1921 6 Sheets-Sheet 2 limin- 17A [den don]? 1,625,779 Apnl 26,1927. VF ALDENDORFF ELECTROMECHANICALLY CONTROLLED TELEPHONE SYSTEM Filed Aug. 26. 1921 6 Sheets-Sheet 3 IAldendmfl Q A ril 26', 1927.

ELECTROMECHANICALLY CONTROLLED TELEPHONE SYSTEM F. ALDENDORFF Filed Aug. 26. 1921 s Sheets-Sheet 4 C 6 a; d3

. [q 9 k) y Inverzfor Iflldendor/fi; av

1,625,779 p 1927' F. ALDENDORFF ELECTROMECHANICALLY CONTROLLED TELEPHONE SYSTEM Filed Au 26. 1 21 6 Sheets-Sheet 5 12203222301: EAZden dorjf ELECTROMECHANICALLY CONTROLLED TELEPHONE SYSTEM Filed Au 26. 1921 6 Sheets-Sheet 6 In z/eraior Ffllderaaorf Patented Apr. 26, 1927.

tliallTED STATES PATENT ()FFlCn.

FRITZ ALDENDORFF, OF BERLIN-WILMERSDORF, GERIVIANY. ASSIGNOR OF ONE- V FOURTH TO PAUL KOLISCH, OF NEW YORK, N. Y.

ELECTROMECHANICALLY-CONTROLLED TELEPHONE SYSTEM.

Application filed August 26, 1921, Serial No. 495,728, and in Austria September 8, 1918.

(GRANTED UNDER THE PRUVISIONS 6F THE AC1 035 This invention relates to an electromechanically controlled system. The object of the invention is to simplify the construction of the connecting devices or switches used in such systems, to prevent the switches from establishing connections with wrong lines, and to enable the subscribers to obtain rapid connections in spite of the fact that only a comparatively small number of switches are provided.

A feature of the system is that a group or groups of switches with calling lines connected to, or associated with the contacts of their contact banks is provided with means by which, when the wiper of a switch is caused to brush over a row of the said contacts, only a certain one of these contacts connected to battery, so that a current will flow through the said wiper and cause its mo tion to be stopped only when the said certain bank contact is reached.

The telephone system according to the invention may comprise a group (or groups) of talking connection calling line switches with calling lines connected to, or associated with, the contacts of their contact banks, and another group (or groups) of called line switches with called lines connected to, or associated with, the contacts of their contact banks, and primary means by which, when the wiper of a calling line switch is caused to brush over a row of its contacts, only a certain one of these contacts is connected to battery so that a currentwill flow through the said wiper only when it reaches the said certain bank contact, and secondary means by which when the wipers of a called line switch are caused to brush over a row of its contacts only a certain one of the called line finder bank contacts is connected to battery so that a current will flow through the said wiper of the called line finder when it reaches the contact that is connected to battery.

Another feature of the invention is that a plurality of calling lines may be simultaneously connected by transitorily engaged line finders to a plurality of numerical switches into which the calling subscribers send their selecting impulses and each of which numerical switches temporarily or permancntl MARCH 3. 1921, 41 STAT. In, 1313.)

associated with one line finder of a group of talking connection line finders, and that means are provided by which only one contact in the bank of a particular talking connection line finder associated with an operated numerical switch can be connected to battery at one and the same time so that the movable contact of the said particular talking connection line finder can only re ceive current through the particular bank contact of this finder that corresponds to the calling line which sends its selecting impulses into the numerical switch associated with the said particular line finder.

A further feature of the invention is that a battery connecting device at all times c0nnects battery only to a contact or contacts associated with one calling line, and to one talking connection line finder, and that the battery connecting device is common to a group of switches and only applies battery to a second calling line and talking connection line finder when the previous finder to which it applied battery has been properly set onto the contact of a calling line.

A further feature of the invention is that the transitorily engaged line finders of one and the same group have a common flat contact bank the talking connection calling line finders may also have a common fiat contact bank. The transitorily engaged line finders are preferably provided with a vertical row of brush carriages which are adapted to be lifted simultaneously by a vertical bar. The talking connection calling line finders may have a vertical row of brush carriages, and when a connection is established a bar is rotated which selects the brush carriage and then lifts the same until its brushes reach a calling line.

A further feature of the invention is thatthe transitorily engaged calling line finders are provided with sub-group relays and that the talking connection calling line finders are provided with bar steering devices and with circuits so arranged that the bar steering dc 'iccs are controlled by the sub-group relays. Controlling wires are provided by which the bar steering devices are controlled and these controlling wires lead directly from the contacts of the subgroup relays to the contacts of the bar steering devices. Each calling line is preferably provided with a. single separate steering wire for setting the talking connection calling line linders onto the calling line and the said steering wire is connected to battery by the common battery connecting device. The sep arate steering Wire may also be used for conducting current into a conversation meter. lhe arrangement according to the invention is preferably such that the calling lines send half their selecting impulses into transitorily engaged called line selectors which mark the line to be called, whereupon a talking connection called line linder has its movable contacts set onto the marked wanted line.

An important feature of the invention is that the Wanted lines are first selected by wanted line selectors composed of a group of small switches whose number of bank contact points is smaller than the number of contact points in the banks of talking con nection called line finders that are set onto selected wanted lines by the said wanted line selectors. For example talking connec tion called line finders with contact banks for 100 wanted lines may be steered onto any one of the 100 wanted lines by two small wanted line selectors each having only 10 bank contacts or contact sets.

The invention is shown by way of example in the drawin Fig. 1 shows a portion. of a group of selectors having a common flat vertical contact bank or in other words a front view of portions of three selectors of the panel type. In this figure 3 brush carriages are shown arranged between a pair of guide bars and behind a lifting bar adapted to lift the carriages to any desired set of bank contacts. The brush carriages and bars of the other two selectors whose bank contacts are represented in F ig. 1 are omitted.

F ig. 2 is a transverse section through the selector panel shown in 1. ln 2 the lower rack end of the lifting bar and a holding pole associated with the same is shown.

Fig. 3 is a perspective view of a portion of a selector panel with brushes cooperating with vertical contact bars let into the front surface of the panel and with individual bank contacts protruding from the layers of insulation between which longitudinal metal strips are embedded.

Fig. l is a front view of a portion of a panel showing the manner in which the vari ous units or divisions of the flat contact bank are held together by pairs of plates displaced with respect to each other.

Fig. 5 shows two brush carriages arranged one above the other, the lower brush carriage being lifted to such an extent that an upwardly projecting extension tilts the brushes of the top brush carriage away from the contacts of the panel.

Fig. 6 is a perspective front view of a brush carriage with one brush broken away.

Fig. 7 is a perspective rear view of a brush carriage with the brushes omitted.

Fig. 8 is a top view of a bar steering device or switch comprising sets of vertical springs.

Fig. 9 is a vertical section of Fig. 8 on the line V VW.

Fig. 10 is a modification of a brush holder.

Fig. 11 shows circuits by which the brushes .of a selector are caused to be set onto the bank contacts in a reliable manner.

Fig. 12 shows a preferred form of coupling roll used for lifting the lifting rods of the selectors.

Fig. 13 shows the circuits of the transitorily engaged calling line finders and of the battery connecting device by means of which the talking connection calling line finders are set onto the proper calling lines.

Fig. l l shows the circuits of the talking connection calling line finders and of a group selector or numerical switch.

Fig. 15 shows the circuits of the transitorily engaged wanted line selectors, the

talking connection wanted line finders, and the battery connecting device by means of which the wanted line finders are caused to connect to the proper wanted lines.

The frame of a selector group consists of vertical bars E, G of angle iron, of horizontal transverse bars F and four longitudinal bars or plates H, I, K, L. The bodies M of the coils of the coupling magnets or rolls P are supported on the longitudinal bar H by means of nuts N (Fig. 1). Journalled in the longitudinal bar are the selecting rods or steering rods U of the various selectors. The coupling rolls are kept continuously rotating by a shaft R driven by a pulley The coils O which encircle the .coupling'rolls do not revolve but are kept stationary with the bodies M of the coils. The selecting rods in addition to gliding in holes in the longitudinal bar H are also journalled inthe longitudinal bars K and L. Near their top ends the selecting rods are provided with ratchet teeth 6 for rotary movement and near the lower ends they are equipped with round collars 7" adapted to be engaged by a pawl D so as to hold the rod in any position to which it may have been raised. The select ing rods are also equipped with selecting fingers r 9 which, when the rod is rotated by the corms-spending rotary magnet with the aid of its armature T, the rotating pawl 1'1. and the rotary teeth 0 are caused to regis ter with a tongue '5 i or etc. so as to be able to lift the particular brush carriage k or 7.1 respectively which is selected by rotating the rod U. It will be understood that ensues between the rod lifter j and the rotating coupling roll results in the el vation of the rod and of the brush carriage 7c selected. Thus, if the finger 9 has been rotated into a position in which its outer end is beneath the tongue al the brush carriage le will be lifted. During its upward travel the carriage glides between two guide rods Z Z9 and the brushes A, B, C, slide upon the conducting bars or strips a 6 0 (Fig. 3) and over groups of contacts a, 7/, 0, until the proper set of contacts a, 7), c is reached when the coupling roll will be deenei ed.

During the upward travel of the selecting rod a holding pawl or detent I) will slip from collar to collar f so that when the coupling roll is deenergized the rod will be held in its elevated position.

In order that the selecting rod maybe elevated from each set of contacts a, 7), c to the next without vibration and in a re iable manner special circuits shown in Fig. 11 are provided. The coupling roll P (Fig. 11) is energized in any suitable manner, as by the closure of the switch m. A current then flows from the positive pole of the battery through the armature n of the relay 0, coupling roll P to the negative pole. The selecting rod U is now cl rated in the manner already described and the brush C slides up on the conducting strip 0 and from one contact 0 to another. During the ascension of the brush C from the middle of a contact 0 to the lower edge of the next contact 0 the contacts 1*, q atlected by he pawl .i) keep apart. But when the brush C ascends from the lower edge of the next contact up to a point in'nnediately beneath the middle of this contact the springs g, r are caused to make contact and a branch circuit is closed from the negative pole through .l, r, Now if. during the time in which the brush ascends from the lower edge of the next coin tact 0 to the middle of the same, the current. path through the relay 0 (positive pole 0, (1),, C, C tpole) is closed and the circuit from the positive pole through m, in P to the negative pole is opened, the coupling roll 1 will be energized in any case by a current from the positive pole through 1 r. P to the negative pole until the brush C reaches the middle of the next contact At this moment the holding pawl D will slip in beneath the next collarf and open the contact springs r, q. Since the relay 0 will be energized at this moment the coupling roll P will be deenergized and the brush C will stop on the middle of the contact c. If, on account of the inertia of the rod, the brush C should be towed beyond the middle of the contact 0 the brush and the rod will drop back and the latter will be held by the pawl D in a position in which the brush C will re.-:t upon the middle of the contact c.

To restore the selecting rod to its normal position further current impulses are sent through the rotary magnet S. The rod is then rota-ted until a longitudinal groove in the rod reaches the holding pawl, when the rod being no longer held by the pawl D is dropped down into its normal position. The brush carriage, as 73 now also drops until its holding arms '0 (Figs. 1, 6 and 7) fall upon the stops 1 on the guide rods Z Z On the brush carriages one arm 1) is arranged at the rear and another arm 0 at the front of the respective guide rod. The stops 'r, 13 are arranged in a corresponding manner. By this arrangement it is made possible for each brush carriage, as 712 to be raised beyond the stops r T of the next highest carriage and up to the stops 9', r of the next highest carriage but one. In this way provision is made for the brushes of each carriage to ascend into the range swept by two further carriages.

lV hen a brush carriage is raised up to the level of the next carriage above it a striker (l of the former strikes against the lower surface of the brush holder 0 of the next carriage in the manner illustrated in Fig. The brush holder 6 is then swung back on its pivot f and the brushes A, ll, C are tilted away from the contact panel.

The tongues i of the brush holders may also be bent in the form of an angle as shown in Fig. 10. The lingers g of the selecting rod will then brush against the surface of the tongue al when the selecting rod turned and will press the ln'ushcs A, 13, C against the contacts or the contact panel. The pressure of the brushes against their contacts may be of any desired mag-- nitude.

The panel-shaped contact bank is made up of metal strips a I1 a 7) Fig. 3, which extend past all the selectors of the selector group. Each metal strip is separated from the next by a strip of insulation. The metal strips have projections a, 7). c which jut out from the front surface of the bank and whose ends are bent downwards. The position of these projections is such that they lie in the paths of the brushes A, B, C. Extending at right angles to the Contact strips (1 Z) (1 Z2 0 are conducting strips (4 b 0, which are let into the front edges of the horizontal strips of insulation. Hence the brushes A, B, C

lltl

establish connections between the conduct ings bars a 6 0 and the different contact groups or sets a 6 0 a 6 0 according to the heights to which the brushes are raised.

The contact banks are preferably made up of horizontal divisions as shown in Figs. 1 and 2. The metal strips and layers of insulation of each division are held together by pairs of plates ii, ii 71, k m Fig. 4. The pairs of plates of the various horizontal divisions are displaced with respect to each other in such a way that the plates of one division project into the gaps between the plates of the neat division. All the divisions are held together in the manner shown in Figs. 1 and 2 between the longitudinal bars K, L by means ot' the rods Z17 Z27 v The brush carriages travel between the guide bars Z Z and are provided with rolls n 17. to reduce friction. In order to obtain a powerful lifting effect with the coupling roll the rod lifter is preferably made in the shape of a blunt wedge and the iron discs at the ends of the rolls are shaped accordingly as shown in Fig. 12. The coils for magnetizing the rolls 1 are provided in substantially the same manner as es alained in connection with Fig. 1, the engagement between P and y' being where the bevelled surfaces contact, the wedge y being so shaped as to clear with its face the magnetizing coils.

The switches described above may be used for diverse purposes. For example they may be used to perform the functions of group selectors connectors, line finders trunk finders etc. in automatic or semiautomatic telephone exchanges.

In a switching arrangement according to the invention the afore described switches may be provided with additional rod steering devices of the kind shown in Figs. 8 vand 9 when the said switches are employed as calling line connectors for establishing tall;- ing connections with calling or called lines. In such cases the rod U is prolonged at its upper end'and provided with a ring Q1 and a projection p l Vhen the rod ll is turned the projection p )resses baclr one contact spring r after another in succession causing the springs r to make contact with their associated springs The insulating body .9 with its pairs of contact springs r is screwed fast by screws upon the longitudinal bar H, Figs. 1 and 2.

Having now described the construction of the switching apparatus, I will proceed to describe a preferred circuit arrangement according to the invention.

A complete diagram is obtained by placing Figs. 13, 1a and 15 beside each other with Fig. l l in the middle. In 13. l and H are two transitorily engaged calling weaves Their number will however be smaller than that of the calling line connectors (Fig. lt) with which they are associated. P are the coupling rolls and A B C D A B C D are the various brushes of the transitorily engaged finders. The contacts a Z2 0 (Z and the conducting strips a 6 0 d are constructed in the manner shown in Figs. 1 and 2. The horizontal di visions of the common contact panels coinprise as many contact strips as are required for 10 subscribers. The transitorily engaged finders l and H of Fig. 13 differ in their construction from the switches shown in Figs. 1 and 2 in that the conducting strips a 6 0 (l are each common only" to one horizontal division instead of to all the divisions of the panel and in that the fingers of the brush raising rods register at all times with all tongues of the brush carriages so that all the brush carriages are raised simultaneously when the rod is elevated. In these transitorily engaged finders no rotation of the rod takes place. To restore the rod to its normal position a holding pawl is withdrawn from the teeth of a ratchet by a restoring n'iagnet d5, whereupon the rod and all the brush carriages drop down into their normal position.

Associated with each transitorily engaged finder I, II is a trunk finder TIT or TV respectively. In the illustrated circuit arrangement each trunk finder has six rotatable brushes. ln Fig. 13 there is also shown a special line identifying or battery connecting device V which serves to prevent the calling line connectors VI and VII, Fi 1 1 from being set onto wrong lines. The calling line connectors or talking connection switches have a flat contact bank or contact panel in common with the transitorily engaged finders. But the calling line connectors differ from the transitorily engaged finders in that they are provided with red steering devices 55,, S and rotary magnets 155 by means of which the steering rocs are rotated in the desired degree. Fig. 14 also illustrates the circuits of a group selector VIII which is constructed as shown in Figs. 1 and 2.

Fig. 15 illustrates a wanted line selector that is only used temporarily in establishing a talking connection, a wanted line connector X, a trunk finder Kl, a line identifying device for preventing the wanted line connectors from being set onto wrong wanted lines.

The wanted line connector is constructed in the same way as the calling line connectors VI. VII. It is equipped with brush *arriages each having four brushes A 13 llHl CJI

C D and with a rod steering device S and a rotary magnet by which the selecting rod is caused to select the proper brush carriage.

The wanted line selector X consists of a number of small switches XIV, XV each provided with a separate rotary magnet 291, 292, each individual switch, XIV, XV is adapted to select any line in a sub-group consisting of, say, ten lines. The particular individual switch or subgroup containing the desired line is picked out by a subgroup selecting switch XIII. Hence, in cases in which the subscribers groups comprise 100 subscribers lines each wanted line selector may be composed of ten individual switches with ten contact points each and a sub-group selector with ten contact points. The wanted line selector may however be composed of two individual switches with ten contact points each, or, under certain conditions, even of only one such ten points switch as will hereinafter be more fully described.

For eacn group of 100 lines two or three or more wanted line selectors and ten wanted line connectors may be provided. Associated with each wanted line selector is a trunk finder XL. For each group of 100 lines a line identifying or battery connecting device XII is provided which is common to all the wanted line selectors of the group.

Associated with each calling line connector VII is a group selector VIII. The number of group selectors may however be smaller than the number of calling line connectors if auxiliary connectors or trunk finders are interposed between the calling line connectors and the group selectors.

For each group of one hundred sub scribers about two or three transitorily engaged line finders I, II are provided and about ten calling line connectors. In cases in which the subscribers groups comprise more or fewer subscribers lines the number of line finders and connectors will be correspondingly larger or smaller. Associated with each transitorily engaged or quick acting line finder I, II is a link circuit finder trunk finder III. IV. Each group of transitorily engaged finders is provided with a line identifying or baltcry connecting device V.

The lines 2, 3 of the Sui'lStt'llJQl'S 1 are connected to contact strips 2", 3 which extend past all the wanted line connectors IX. Associated with each subscribers line is a test wire 5 for the transitorily engaged finders and the calling 1i .e connectors, a test wire 1 for the wanted line selectors and the wanted line connectors, a stopping and meter wire 6. and a stepping Wire for the wanted line connectors. Hence our wires 2". a") 13) extend past each group oi calling inc connectors and Your wires 52', 3", 4t, 6 extend through each group 01 wanted line connectors (Fig. 15).

All the other details of the circuits will appear in the following description of the operations which occur in establishing atalkin; connection between two subscribers.

It will be assumed that the subscriber No. 1 desires to connect his line with that of the subscriber No. 111.

The calling subscriber '1 in raising his receiver "from the hook closes his line circuit and a current will flow from the positive pole of the exchange battery through the upper winding oi" the line rela 7, contact 12 ot' the cut off relay, 2, 1, 3, contact 8 of the cut oil relay, lower winding of the line relay '3' to the negative pole. The line relay 7 loses its contacts 10 and 15 and opens the contact 14. At the contact 10 circuits are closed which include the coupling coils P I? of the transitorily engaged finders I, II and the rotary magnet 16 of the line identifying device V. These circuits may be traced from the positive pole through 10, P 1 1, a l), to the negative pole; "from the positive pole through 10, P 72, 71 to the negative pole; and from the positive pole through 10, 91, 16 to the negative pole. All the brush carriages or sets of brushes A, B, C, D of the quick acting finders will now be caused to travel upwards over the contact bank by the continuously revolving excited coupling coils I, P The rotary magnet 18 imparts rotary movement to the wipers 17, 18, 19, 20.

The steering rod of the one quick acting finder, say II, is displaced with respect to the rod of the other finder I in such a way that its brushes are one step behind the brushes oi the first finder. By this measure the contingency is prevented from arising that both finders strike upon the same calling line at the same moment.

By the closure of the contact 15 the positive pole of the battery is connected through the winding 9 oi the cut off relay and through 15 to the test wire 5. By the opening of contact 1 1 the calling line is made to test busy to the wanted line selectors because current will be prevented from flowing from a wanted line connector through a wire 41 and through the cut oil relay 9 to the posilive pole.

As soon as a brush. say C, of a quic act ing finder reaches the test contact 0 of a test wire 5 connected to the positive pole a current will flow from the negative pole through the contact 21 of the relay 26 of the trunk finder III, wire 40, contacts 41, 46, 51, relay windingconducting strip 0, brush C contact 0, test wire 5, contact 15, cut off relay 9 to the positive pole. The relays 15 and 9 are both excited. The relay 4:5 closes its contacts 4:33 and opens its contacts 41 and 4+. lly the opening the contact "ii. the

connection of the ren'i'aining test relays 50 with the wire 40 and the negative pole is broken and from this moment no other test relays can be energized. The circuits of the test relays 45, 50 of each quick acting tinder are arranged in such a manner that no more than one test relay can ever be energized at the saine inonient. lift it should happen that two relays e5, 50 are simultaneously energized the second relay 50 will be immediately deenergized again a moment later by the opening of the contact 11 ot a first relay But it the relay 50 has once pulled up its armature no subsequent energi- Zat'ion of the relay 4-.5 can take plac because this hitter will be out ofi from the battery supply lead 71 by the opening ot a contact s.

l'Vheii the relay 4C5 has closed its contacts 42, e3 in the manner described and has opened its contacts e1, ate: a current flows from the negative pole of the battery through 21, 40. 42, relay 52, to the positive pole and another current flows from 10, through and apart t the winding 45 throi'igh 0 C 0 and through the cut oti' relay 9 to the positive pole. By the application of the negative pole or the wire aO to a few turns of the winding 41-5 the test potential on the test wire is lowered in a known manner and the busy condition of the calling line is thus established to prevent its seizure byot'lier quic acting line finders.

By the opening of the contact 1 1 the coupling coil P is deenergized so that the brush carriages ot the quick acting tinder I are all stopped. On the simultaneous energization of the cut as relay 2) and the opening of the contacts 8, 12 of this relay the line relay 7 is deenergized. A relay 68 which was energized on the closure of the contact ot the line relay will now be deenergized if no other line relays are energized and it will close its contacts 69, 70. The contact 70 closes a circuit which extends from the negative pole through 71, 72, 70, release magnets 73 and through the restoring relay 75 and the otlfnornial contact 7 1 to the positive pole. The relay 75 closes a locking circuit for itself at its contacts 76 and now keeps the circuit (negative pole, in, 7 positive pole) oi the release magnet closed until the steering rod of the quick acting tinder I]. drops hack into its normal position and the circuits oi the magnet 73 and the relay are opened. by the oil' normal switch 741.

the encrgisation of the release magnet 45 or of the relay (it; at the quick acting tinder I that has connected to the calling, line 2, 3 does not iitlZiO place at this time because the connection between the contact 69 and the negative pole is broken at the contact 1 1-.

By the closure of the contact 12 a circuit is closed from the negative pole through 21, 40, 4:2, relay 52, to the positive pole. The

rename relay 52 opens the contact 51 and thus interrupts the indirect connection which would extend from 4:0 through the rear portion of the winding -16 and through 5:, to the wind.- ing 50.

By the closure oi the contacts (50, ($1. the calling line 3 is connected through the brushes A B contacts 60, 61, wires 78, 79 wipers 33, 34, to the wires 8? which lead. to the group selector VIII or the calling line connector VII.

The trunk finders III, IV always keep their associated finders 1', 11, connected to a tree calling line connector VI, VII by means (it circuits which will be hereinat'ttmore tully described. The arrangement may also be such thata trunk finder is started at the same inonient as its associated li-ne finder and then connects its line: finder to the first tree trunk found by its wipers.

By the; closure of the contact 63 a circuit is prepared for the stopping ot' the wipers 17, 18, 19, 20 of the identifying device V on the wires 86, 87, 88, 89 that lead. to the quick acting finder l. or to the associated trunk tinder 111. When the wipers 17 strikes upon the wire 86 a current flows from the positive pole through the closed contact 63, wire 86, wiper 70 and through the relay 90 to the negative pole. The relay 90 opens the circuit 01' the rotary magnet 16 and its contact 91 so that the wipers 17, 18, 19, 20 are stopped. The contacts 9:2, 9+1 are closed by the relay 90. The contact 92 prepai a circuit which operates to stop the rotation of the brush liftin rod or of the arm S attached to the rod of the callingline connector VII to which the line tinder I is connected by the trunk finder H1.

The contact 93 prepares a circuit which causes the brushes of the calling line connector VII, lifted by the coupling coil P to stop at the proper calling line. The contact 9% cooperates with the contacts 92 and 93 in the said prepared circuits which control the setting operation of the rotary switch of the brush lifting rod and the biting; opera: tion by which the brushes of the callinp' line connector are set onto the proper cailing line.

The manner in which the calling line 2 fl is c-oiinectcd through the quick acting lino finder and the associated trunk finder ill to the wires 82 d3 of the group selector V111 has already been explained. As soon as this connecting operation is completed a current flows from the positive pole to the left winding of the line relay 100, contact 101, of the relay 103, 83, wiper 34-, ot the trunk finder III, 79. 61. at. A 2, 2. subscriber station 1, 3, 3, L B 7)", T9, 82, contact 106 of the relay 103, right hand winding" of the line relay to the nega tive pole. The line relay closes its contacts 118, and opens the contacts 119, 121. A

current then flows from the negative polo through 118, release relay 112, resistance 113 to the positive pole. The change over relay 111 which was energized by a current 110111 the negative polo through 118, 11-1, 115 to the positive pole short circuited by a contact 120 so that tor the time being its contacts 116 and 117 remain in their normal positions. The release relay 112 closes its contacts 109, 110 and opens the contacts 107, 108 and 111. At the contact 10!.) the release relay closes a locking circuit for ilsell which is maintained until the contact 118 is closed at the tinish of the 'onversat-ion. A current also flows at this time "from the positive pole through 110, 110, 1-1-1, rotary magnet, 155, of the calling line connector, interrupter 160 to the negative pole. The rotary magnet now turns the brush lilting rod of the calling line connector and this rotary niol ion accompanied by the rotation of the rotary control switch S which closes a i'resh pair of contacts 151 at each rotary step until a tinger of the brush lifting rod registers: with the proper brush carriage. As soon as this happens a current flows from the negative pole at the identifying device V (Fig. 13 through the contact 91 and through 20, S0, 35, 85, relay 1% of the calling line connector, 160, pair of contacts 154-, steering wire 161, contact 6 1 of the subgroup relay 52, wire 87, 18, 92, to the positive pole. The relay 14,4 of the rotary control switch S is energized and opens the contacts 1 11, 1 17 whilst it closes the contacts 142, 1 13, 145 and 146. At the contact 1 11 the circuit of the rotary magnet 155 is opened and at the contact 141-2 the coupling coil circuit P is closed (positive pole, 110, 1&2, 153, P negative pole). 11? during the operation of the rotary control switch S other brush lifting rods with their rotary control switches S are rotated no such rotary control switch can be stopped on the wire 161 because it will not have any battery connection extending from the minus pole through 94 of the identifying device and through 91, 35, 85 to its relay 111. it is thus seen that the only rotary control switch that can be set onto the line 161 one that has been associated with the wire 161 by means of a quick acting finder or a subgroup relay 52 and whose lead to its relay lei-4c has been connectei'l by an identifying device V to the negative pole. Thus all possibilities of wrong connections being established by the calling line connectors are precluded by the identifying device V which applies the battery to only one contact in the cont-act bank 01 a started calling line connector and to the hunting wiper or relay 144 of this connector at a time.

The relay 144 closes a locking circuit for itself atthe contacts 143, 1 15 which extends from the negative pole through 109, 1-15, 1 13, 157 to the positive pole. By the contact 1216 the relay 11- 1; connects the negative pole to the relay 11-6. On the brush D now rising up to the contact D 01: the stopping wire 6 ol the calling line a current will flow through the relay 11-18 "from the negative pole through 100, 1-1-6 winding 1-18, wire 161., lead (/2 brush D contact (Z stopping wire 6, contact (1 ol the quick cling tinder .1, brush 1), contact 62, 88, wiper 19 ot' the line identillving device V, 93, resistance 95 to the positive pole. The hunting brush 1), is precluded from finding any stopping wires connccted with the positive pole oil the battery excepting the stopping wire 6 ot the subseribers line whose call gave rise to the starting of the calling line connector VII, because the said starting wire 6 is the only one which is connected through the contact )3 of the identifying device V to the positive pole of the battery.

..'\s soon the relay 11-8 is energized in the manner described a new circuit is closed for its right hand winding which extends from the negative pole through 109, winding 148, 119, 162, c, C, 5, 13, cut oil relay 0 lo the positive pole. The coupling coil 1 is deenergized at the contact 153 and the calling line 2", 3 is connected through the brushes A, B connecting strips (1 5, contacts 151, 152, to the wires 82, S8 and the line relay 100. At the contact 150 the relay 1 1-8 closes a starting circuit tor the trunk finder III. This circuit extends from the positive pole through 150, 8 1, 36, relay 37 to the negative pole. The conta its 5, 39 are closed the latter completing the circuit of the release magnet 15 (negative pole, 39, 35, 5, positive pole) and the former closing a circuit of the relay 26 (negative pole, 38, 26. positive pole). The quick acting tinder I is restored to normal by its release magnet whilst the trunk tinder 111 is caused by the deenergizatiou of the relay and the closure of the circuit of its rotary magnet 30 (negative pole, 29, 25}. 330, positive pole) to impart rotary motion to its wipers until these latter strike upon a calling line connector or trunk that is neither engaged for a conversation nor has been seized by another trunk tinder IV. When the wipers ot' the started trunk tinder have found such a trunk or calling line connector the contact 11-7 of the relay let-'1 and a contact 1 11 ot the group selector associated with the disengaged calling line connector will both be found closed. A current will then [low from the positive pole through 111, 1417, relay 140, S1. 32, contact 21- ot the relay 26 to the negative pole. The relay 1410 is then energized. It the calling line connector has not been seized by any other trunk tinder a current will flow from the positive pole through 139, S0. 31, 22, relay 27 to the negative pole. The relay 27 is energized. But thus energization could not take place if another trunk finder such as IV had already seized the same calling line connector because then a current would flow direct through 31, and a back contact 21 of the other trunk finder to the negative pole of the battery instead of first flowing through the relay 2'? oi": the hunting trunk finder.

But it the relay 2''? is energized the circuit oi the rotary magnet 30 is opened at the Contact 29. At the contact 28 the locking circuit of the relay 25 (positive pole, 2t", 25, 28, negative pole) is opened. Hence all the parts 01 the trunk finder 111 and the quick acting line finder 1 retu'rnto their normal positions and the associated trunk finder connects its quick acting finder I to a free unseize'd calling line connector.

0n the energization of the relay 26 the negative pole of the battery was disconseated at the contact 21 from the wire a0 and therefore also from the subgroup relays e5, otthe released quick acting finder I, so that this finder, in dropping back to its normal position, is prevented from est-ah lishing a connection with any line whose wires 5 may be in a calling condition. During the period in which the calling line connector V11 was set onto the calling line by a prior rotary motion of the rotary control switch for the purpose of selecting the subgroup of the calling subscriber and by a subsequent elevating motion caused by the coupling coil, the calling subscriber may have been able to send selecting irn pulses through the line relay 100. All the selecting impulses which may still have to be sent to the relay 100 after the calling line connector has been set onto the calling line, will flow without being interfered with in any way over the following path: from the positive pole through the left winding of relay 100, 101, 83, 152, 170, a A, a, a", 2, subscriber station 1, 3, 3", 6 B 6 171, 151, 52, 100, right winding of the relay 100 to the negative pole.

At each interruption of this circuit dur ing the dialling operation the armature of the relay 100 falls back. The contacts 118, 120 are opened and the contacts 119, 121 closed. As soon as the contact 121 is opened the by-path which short circuits the change over relay 111 is opened so that the change over relay is energized to close its contact 116' and open the contact 117. During the vibration ol the armature ot the relay 10o cliifected by the selecting impulses the momentary short circuitings ot the change over relay 114 efi'ected by the contact 120 do not affect the energization of the change over relay so that it keeps its armature attracted.

At each retraction of the armature of the relay 100 a current impulse flows from the neaawa negative pole through 109, 121, 110 and to rotary'magnet 172 to the positive pole. The brush moving rod of the group selector is thus rotated until one 01 these fingers registers with the proper brush carriage, which in this case is the carriage which supports the set of brushes A B", C. The first current impulse from the negative pole through 109, 121 and 116 also flows through the relay 123 to the positive pole. The right winding of this relay closes a locking circuit for itself (positive pole, right winding 12 1, 109, negative pole) which remains closed up to the end of the connection. By

- the closure of its contact 122 the relay 123 prepares a circuit for the coupling coil P When all the selecting impulses (111 this case one impulse, because the first hundred is being selected) have been sent in the relay 100 maintains its armature in its attracted position. The contact 120 now keeps the change over relay 114 short circuited again so that this relay let its armature fall back to open the contact 116 and close the contact 117. A current then flows from the negative pole oi the battery through 117, 122, 128, P to the positive pole. The coupling coil P being energized now causes the brush moving rod to rise so that the brushes 1'1 13 C slide upwards over the contact bank. The upward motion of the brushes continues until they reach a trunk line 200, 201, 202 which is not engaged for a conversation but which is connected by a trunk finder X1 to an idle wanted line selector K (Fig. 15). A current then flows from the negative pole through 109, 180, test relay 125, conducting strip 181, test brush 0, test wire 202, lower winding 01 relay 250 (Fig. 15), wiper 241, relay contact 252, 20-1, wiper 290 of the wanted line selector to the positive pole and battery. The testrelay 125 and the relay 250 are energized. The former closes its contact 126 and the latter closes its Contact 221. The test relay 125 short circuits the upper part or" its winding and thus lowers the potential on the test wire 202 so as to make the seized trunk test busy, whereby other group selectors are prevented from seizing the trunk 200, 201, 202. If he wanted line selector X had been connected with the trunk line the group selector would not have been able to seize it because there would. then have been no energizing circuit for the test relay 125 through the wiper 245 1 of the trunk tinder. In a similar manner, no circuit would have been established for the test relay it the wanted line selector had been engaged because the test circuit would then have been open at the contact 26a or at the wiper 290. This will be more :r'ully explained later.

As soon as the test relay 125 is energized it opens the circuit 01 the coupling coil at its contact 1.28. The branch circuit of the cou pling coil (negative pole, q, p, 1", positive pole), which, as was previously explained, serves to eli'ccl the proper setting of the contact brushes onto the middle of each set of contacts is also interrupted when the test relay 125 is energized so that the brush carriage or brushes 11", 15, C are stopped on the trunk 200, 201, 202. At its contact the test relay closes a circuit for a relay 10;? which extends from the positive pol-e, through 182, 127, 108 to the negative pole. This relay connects the wire 83 of the trunk to ground connected with the positive pole of the battery and the other wire 82 through its contact 105 to the wire 18% so that a current will now flow from earth through 102, as, 152, 170, cf, A in, 2", 2 (Fig. 13) subscriber station 1, 3, 3', I), B 6 171, 151, as, 105, 1841, 129, 182, 201, 306 (Fig. 15) 243, 251, line relay 269 of the wanted line selector to the negative pole.

At its contact 101 (Fig. 1 1) the relay 108 or a circuit for the left winding of the y 100 (negative pole 1041, 100, positive p lo) and thus prevents the deenergization the relay 100, which would result in the restoration of the group selector and the calling'line connector to their normal positions as will be hereinafter described.

The line relay 269 of the wanted line selector, which, as has just been pointed out, is energized by a current flowing over the calling subscribers line, closes its contacts 270, and opens the contacts 271, 273. At the contact 270 the circuit of the release relay 268 is closed, this circuit extending from the negative pole through 270, 268, resistance 278, to the positive pole. The release relay closes a locking circuit for itself at its contact 267 (negative pole, 268, resistance 278. positive pole). A circuit is also closed for the change over relay 275 (negative pole, 270, 275. 279, positive pole) but the change over relay is kept short-circuited for the time being by the contact 272. The release relay 268 closes its contacts 267, 27 1 and opens its contacts 264, 265, 307 whilst the change over relay remains deenergized.

The calling subscriber now sends in his tens selecting impulses for the purpose of setting the wanted line selector unto the proper lens group. At each interruption of the dialling circuit the line relay 269 is deenergiaacd and the contact 272 is opened to emovc the short circuit about the change over relay This relay is energized (negative pole. 267, 275. 279. positive pole) and closes its contact 276 whilst opening the ci'intact 277. is long as the dialling inipulses flow through the line relay 269 its armature will vibrate and cause momentary shin-t circuitings of the release relay by the contact 271 and similar short circuitings of the change over relay 275 by the contact 272. But these intuncnlary short circuitings do not suilicc to deencrgizc the said relays so that they keep their armatures attracted. At each closure of the contacts 271, 273 a current impulse flows from the negative pole through 267, 273, 276, 285, rotary magnet- 287, 274, 309, wiper 290 to the positive pole. Each said impulse causes the subgroup selector X111 to be rotated one step, and this step by st p movement continues until the proper subgroup (which in this case is the first subgroup or tens group or the first units switch which selects the lines within the first tens group) is reached. The Wiper 288 then establishing connection with the rotary magnet 292 of the first units selector XV and the wiper 289 establishing connection with the stopping wire or guide wire 310 that leads to the rotary control switch S of the wanted line connector IX. The wiper 290 is set onto a segment 312 which is connected with the magnet 287 or the relay The wiper 290 and the segment 312 serve to restore the wanted line selector to its normal position as soon as the selector has performedits function of setting or guiding a wanted line connector onto the proper wanted line lVhen the first tens selecting impulse is sent in the current flows not only through the rotary magnet 287 but also from the negative pole through 267, 273, 276, relay 282 to the positive pole. The relay 282 closes a locking circuit for itself at its contact 281 (negative pole, 267, 3141, 281, 282, positive pole) and at its contact 280 it prepares a circuit for the relay 283.

After the tens impulses have been sent in,

i. e. after the first tens impulse in the present instance, the line relay 269 keeps its armature att acted. The change over relay 275 is then short circuited by the contact 272 so that it is deenergized and causes a current to flow from the negative pole through 267, 277, 280, relay 283, to the positive pole. The relay 283 is energized and closes a locking circuit for itself at its contact 284 (negative pole, 267, 281, 283, positive pole). At its contacts 285, 286 the relay 283 disconnects the wire 315 from the rotary magnet 287 and connects it to the wiper 288. The calling subscriber now sends in the units selecting impulses causing the armature of the line relay 269 to vibrate. The change over relay 275 is energized again and current in'ipulses flow from the negative pole through 267, 273, 276, 286, 288 to the rotary magnet 292 of the first units selector, 1, c. to the selector with which the wiper established connection, and to the positive pole. Since the calling subscriber desires to connect with the line number 111 he will only send in one units selecting imltd pulse, so that the rotary Inagnet 232 only receives one current impulse and the wipers 315, 316 are set onto the test wire a" and the guide wire 6 associated with the desired suhscribers line.

The line relay now maintains its contacts 270, 272 closed again so that the change over relay 275 is deenergized again and closes its contact 319 to connect the negative pole through 207, 319 to the test relay 203. the selected line is free the test relay will be energized by a current which flows from the negative pole through 267, 319, 293, 310, test wire l and then through the contacts of the line relay and through the cut 00? relay associated with the called line (the said relay being similar to the relays 1st and 9 (Fig. of the calling line) to the positive pole. It the called line is already on gaged by another wanted line selector the potential or the test wire will not suthce to energize the test relay 293. It the wanted line should just happen to be calling another subscriber the potential on the test wire t will also be lowered by a test relay 45 or 50 (Fig. 13) of a transitorily engaged line finder or by the relay 148 of a calling line connector (Fig. 1e) to such an nitent that the said potential will not sutiice to energize the test relay; or it the wanted line that is just in the act of calling another line has not yet been connected to a group selector by a quick acting line finder or a calling line connector, the contact let of the line relay oi: the said. wanted line will be open so that the? test relay 293 out the wanted line selector testing the wanted line will not be energized because its circuit is open.

But if the test relay 293 is energized in the manner described it will close the con tact 295 and lower the potential on the test wire 4 to such an extent that no other Wanted line selector will be able to connect to the selected line.

It has now to be mentioned that, when the line relay 209 and the release relay 263 were energized a circuit was closed from the negative pole through the interrupter 266, 391, 330, 300, rotary magnet 305 to the positive pole. tatesthe wipers 296, 297, 293, 200 of the identifying device X11 until the wiper 296 strikes upon a wire 331 which is connected by the contact 294 011 a test relay to the positive pole. The relay 301 attracts his armature and closes the contacts 302, 303, 304 whilst opening the circuit of the rotary magnet 305 at the contact 300. By the con tacts 303, 30a the negative pole of the hattery is connected to the two guide wires or stopping wires 310 and 0 (by way of 30%, 299, 280 to 310; or through 303, 293, to 6) and the contact 302 connects the positive pole of the battery to the guide wire 332 (through 297, 2 16 to 332).

The rotary magnet 305 ro By the contact 20st an energizing circuit is closed for the rotary magnet 333 of the rotary control switch S which circuit extends troin the positive pole 204:, 24:7, 232, 333, interrupter to the negative pole. The rotary magnet 333 now turns the brush lifting rod until the pair of contacts 330 is closed which is connected to the tens guide wire 310 that is the guide wire that leads to the subgroup selector XIII. A current then flows troin the positive pole through 302, 297, 2 10, 332, relay 23a, contact springs 336, subgroup or tens guide Wire 310, Wiper 289 of the wanted line selector, wiper 209 oi the identifying device to the negative pole. Since the relay 23st of only one single one or all the called line connectors is connected to the positive pole, and ot' all the tens guide wire only a single one 310 is connected to the negative pole only the one relay 23% of the wanted line connector that connected to the identifying device can be energized even it several wanted line connectors are operated at the same time. The relay 23 i closes its contacts 233, 235, 236 and opens the contact 232 and thus the circuit of the rotary magnet At the contact 233 the circuit of the coupling coil P is closed (positive pole 294, 2&7, 233, 242, P, negative pole) and the coupling coil now causes the brush lifting rod to be elevated so that the selected set of brushes A B C D travel upwards and wipe past the contacts of the contact panel or bank until the guide circuit brush D reaches the units guide wire 6 associated with a line of the wanted subscriber No. 111. Since the units guide circuit relay 28? of only a single one of the wanted line connectors of the particular group is connected through 302, 297, 2&6, 332, 230 to the positive pole and only the one units guide wire 6 of the wanted line No. 111 is connected by the identitying device XII to the negative pole (through 303, 293, 315), it is only possible for the one relay 237 of the particular wanted line connector that is connected to the identifying device to be energized. The relays similar to 237 of other wanted line connectors cannot be energized by a current through the units guide wire 6. The relay 234 had closed a locking circuit for itself which extended from the positive pole through the contact ot the relay 250, 35 1, 235, 23a, 330, 310, 289, 299, 304-, to the negative pole. The relay 237 is now energized by a current from the positive pole through 222, 3 l1, 235, 230, 237, guide circuit brush D guide circuit contact cl, guide wire 6, 315, 298, 303 to the negative pole. The relay 237 closes its contacts 238, 23,0, 240, 2-11 and opens a circuit of the coupling coil P at the contact The branch circuit (positive pole p P negative pole) is also opened as soon as the brush D reaches the ion middle of the contact (Z and the set of brushes A B, C, D stops on the contacts a", b 0 (Z of the selected line No. 111.

By the contact 238 the lower winding of the relay 237 is included in a circuit which contains the cut oil relay oi the selected line, this circuit extending from the negative pole through 395, lower winding, 238, 239, 343, C 0 test wire 1, contact 1 1 of the line relay and the cut oil relay 9 of the selected subscriber (Fig. 13) to the positive pole of the battery. The resistance of the lower winding of the relay is such that the potential on the test wire 1 is lowered sufficiently to prevent the wanted subscriber line from being connected to or seized by a quick acting finder.

The contact 240 of the relay 237 closes a circuit for the relay 204 which extends from the negative pole to 2&0, 340, 225, interrupter 208 to the positive pole and the relay 259 of the trunk tinder X1 is also energized by a circuit extending from the negative pole through the contact 2&0 ot' the relay 237, 381, 24:9, 259 to the positive pole. By means of its contact 205, 206 the relay 20salternately connects the ringing current generator 207 and the ringing cut oil relay 209 to the line 380 that leads to the called subscriber No. 111, and the relay 259 closes a circuit for the rotary magnet 882 ot the trunk tinder XI, this circuit extending from the negative pole through 258, st, 382 to the positive pole. The brushes or wipers 213, 21st, 2H), 246, 247, 2 18, 2&9 are now moved on until the Wiper 2&5 strikes a wire 381 that leads to a wanted line connector which is neither seized by a group selector nor a second trunk finder and which is not engaged for a conversation. If the wanted line connector has been seized by a group selector the contact 224 will be open; if the wanted line connector is being used for a conversation a busy condition will he established by the opening of a contact The circuit leading from the negative pole through 2 15, 38s, relay 229, 335 and to 224-. to the positive pole will under these circumstances, not be closed. But as soon as the wiper strikes a wire 384 which extends through closed contacts 335, 22 1 to the positive pole the relay 22?) is energized. it closes a circuit leading from the positive pole through the resistance 231 and through 280, 3823, 24:8, 256, relay 257 to the negative pole if the wanted line connector has not been already seized by another trunk tinder; for in such a case the current, instead of flowing through the relay 257, would pass through the contact 255 of the other trunk finder to the negative pole. Hence, in a case like this, the relay 25? would remain deenergized. But when a wanted line connector that is neither being used for a conversation nor has been seized by any switch, is found the relay 257 is energized in the manner described. The circuit of the rotary magnet 382 and ot the relay 259 is opened at the contact 258 and the wipers 2413 to 249 stop on the contacts leading to the free wanted line connector and thus eeize it.

It must now be mentioned that as soon as the relay 259 was energized to open the contac 251, the line relay 269 was dcenergized. This relay then closes the contact 271 and thus short circuited the release relay 268 which closed the contacts 265, and opened the contact 27 1. The opening of the contact 267 results in the decnergization of the change over relay 275 and the relays 282, 28

Restoring impulses now flow from the negative pole through the interrupter 266, 265, 261, 288 through 292 to the positive pole so that the wipers 315, 316, 317 off the particular units selector used, are stepped forward until the wiper 317 reaches its normal position in which it makes connection with the negative pole, a current then tlows from the negative pole through 817, 386 and through the wipers 387 of all the other units selectors which are in their normal positions and through 2588, relay 263, segment 812, wiper 290 to the positive pole. The relay immediately opened the circuit of the magnet 292 at the contact 261 and at its contact 262 it closes the circuit of the rotary magnet 28? which extends from the negative pole to the interrupter 266, 307, 262, 287, 312, 200 to the positive pole. The rotary magnet 28? new steps the wipers 288, 289, 200 of the sub group selector XIII round until the wiper 290 reaches its normal posi tion and opens the circuit oi" the relay 263 and the rotary magnet 287 by leaving the segment 812. Since the test relay was also immediately deencrgizcd on the deenen gization of the release relay and the opening of the contact 26?, all the parts of the wanted line selector will now have been restored to their normal positions. The wanted line :elector will now also have been connected to a tree wanted line connector in the manner already described and can be used for setting up a new connection.

The ringing current periodically cornice"- cd to the wanted line by the relay 20-lflows from the negative pole oi the ringing current generater 207 through 205, 210, I380, wiper A (N -wire 2' to the called subscriber and back to 8 Z)". B 2-300, 216 to the positive pole. As soon as the called subscriber responds and the contact 206 is closed a current flows from the negative pale through 2-l1, relay 209. 206, 210. 380. A a, 2, called station back through 3. 7), B. 390, 216. to the positive pole. The relay 20$) is energized and closes the contact 208 whereby a relay 21? is energized by a circuit extending from the negative pole through 203. left winding 21? to the positive pole. The relay 211' closes its contact 218 to energize the relay 227 by a circuit extending from the negative pole through 218, 227 to the positive pole. By this means a circuit is closed which 0:;- tends from the positive pole through 226, right winding of the relay 227, relay 213 to the negative pole. The relay 213 closes its contacts 211., 212, 21 1, 215 and opens its contacts 210, 210. The inging relay 20-1 is cut out at the contact 225 and the ringing cut oil? relay 209 is disconnected at the contact 210. At the contacts 212, 211 a new circuit is closed for the relay 217 which extends from the positive pole to the left winding of 217, 214, 390 to the wanted subscriber and back through 380, 212, right winding of 217 to the negative pole. At the same time a circuit which extends ba'cl: to the group selector is closed this circuit extending from the negative pole through the right windii'ig 01' 217 and through 212, 211, 200, 1 183, 131, lower winding 01 relay to the posh tive pole. This circuit which is the sistering circuit energizes the relay which closes a locking circuit for itself the contact 130 (positive pole, relay 131 *5, 130, 180, 109, negative pole) and ener nos the relay 131 whilst closing the contact 137. This contact directly connects the positive pole to the wire 161 and the meter 11 ct a calling line is then actuated by a current which flows from the positive pole through contact 137, 101, (1, D (Z ('3, meter 11 1 13) to the negative pole. The conversation is thus counted.

The relay 131 opens the contacts 1 2, 134-, 129 and closes 133, 130. By the opening 01? the contact 132 the relay 103 is dcenergized to close its contact 101, 106. Current is now again fed through the windii'igs oi. the relay 100 to the transmitter 01 the calling sub scriber and voice currents now .tlow from the calling to the called subscriber over the following circuit: 1, 2, 2 (Fig. 13 and 11), (1*, A 01 170, 152, 101, condenser 700, 133, 183, A 200, 211 (Fig. 15), sec, 11 a 2, wanted subscriber back over 3, b", 13 390, 215, 201, B 182, 130, condenser, 106, 82, 151, 171, 6 B 5*, a", a, 1.

If the Wanted subscriber replaces his receiver first at the end of the conversation the transmitter fed relay 217 (Fig. 15) in the wanted line connector is deeuergized to close a contact 219 whereby the negatiye pole is directly connected through 219, 228 to the end of the winding of the relay 250 and this relay is short eircuited so that its armature drops back. By this means a circuit for the rotary magnet ot the rotary control switch S is closed, this circuit extending iroin the positive pole through 223, 334, rotary magnet 333, interrupter through the negative pole, and causing the rotary magnet to turn the brush lifting rod until it reaches its normal radial position in which the con ee-awe tacts 334; are opened to deene'rgizc the rotary magnet 333. The brush lifting rod then drops down into its normal longitudinal position and the brushes also drop down into their normal positions.

At the contacts 395, 222, the locking ci1' cuit oi the relays 237, 213, 227 and the circuit of the cut off relay 9, (Fig. 13) oi the called line are also opened, so that all the parts 01' the wanted line connector 1X go back into their normal positions.

1115 the contact 221 the circuit extending back co the group selector through the test wire 202 is opened to deenergize the test relay 125 (Fig. The group selector and the calling line connector are restored as soon as the calling subscriber replaces his receirer to deenergize the relay 100. The re ease elay 112 is then short circuited at the contact 119 and opens the contact 109. This interrupts the locking circuits of the relays 14:8, 123, 135, 131 and also the locking circuit of the test relay 125 if it should not have been already deenergized by the wanted subscriber having replaced his receiver. This would also cause the relay 250 of a wanted lino connector to be deenergized so as to restore the wanted line connector.

By the closure of the contact 108 of the release relay the rotary magnet 01' the rotary control switch is energized by impulses flowing; "from the negative pole through the interrupter Ur, 108, 100, rotary magnet 172 to the positive pole. The rotary magnet then turns the brush lifting rod until it reaches its radial normal position in which the contact 100 is opened to interrupt the circuit of the rotary magnet.

At a contact 107 the restoring circuit of the calling line connector is closed, this circuit extending from the negative pole tl'irough the interrupter 150, rotary magnet 155, 101, 107, 102, 157 to the positive pole.

he rotary magnet turns the brush lifting rod until it reaches the radial normal posi tion in which the contact 157 is open. The brush lifting rod then drops down into its longitudinal normal position.

111 order to give the calling subscriber a busy signal a busy tone device 01 a well lrnown kind may be connected through a front contact on the relay 283 (Fig. 15) and a back contact 01 the test relay 293 of the wanted line selector and through a condenser to the wire 4-20. The busy tone current would then flow over the wire 201 to the calling subscriber, who would replace his receiver and deenergize the relay 269. This would result in. the restoration oi the wanted line selector to its normal position in the manner already described.

it rin ing signal, which indicates to the caliing; subscriber that a ringing current is actually flowing to the wanted subscriber could be periodically connected to the wire 200 through a trout contact on the relay 204.

From the foregoing description it will appear that the switches Vi and VII, Fig. 1st, may be called ca lling-lincaronnectingswitches, and that the switches i. ll, Fig. 13, are calling-lineimirkirig-switches that electrically mark the calling lines to which the switches VI, Vii sliall connect. The calling-line-connectings ritches VI, VII are prevented from connecting to improper marked lines by the switch Y which is com mon to a group of callinglincanarkingswitches.

The switches IX, Fig. to, may be termed wanted-line-connectirig-switches, and the switches X, Fig. 15, wanted-line-marking switches. The switches IX, Fig. 15, are prevented from connecting to improper marked lines by the switch XII which is common to a group of wanted-line-markingswitches.

The contact strips a 5 and a 6 Fig. 3, may be called line contact strips.

The terms used in the three preceding paragraphs will he adopted in the following claims.

I claim:

1. In a telephone system, lines, calling means, calling-linemarking-switclres for electrically indicating that a line is calling, switches for electrically marking wanted lines, calling-lineconnecting-switches :tor connecting to calling lines, wanted-line-connecting-switches tor connecting to wanted lines, a switch common to a group of calling line marking switches and adapted to set the calling line connecting switches onto the calling lines marked by the calling-lineniarking-switches, and a switch common to a. group of wanted line marking switches and adapted'to set the wanted line connecting switches onto the wanted lines marked bythe wanted line marking switches.

2. In a telephone system, lines, calling means. calling-line-1narking-switches for electrically indicatingthat a line is calling, switches for electrically marking ranted lines. caHing-line-connecting-switches tor connectingto calling lines. wanted-line-connecting switches for connecting to wanted lines, a witch common to a group of calling line marking switches and adapted to set the calling line connecting switches onto the calling lines marked by the calling-linemarking-switches, a switch common to a group of wanted line marking switches and adapted to set the wanted line connecting switches onto the wanted lines marked by the wanted line marking switches, switches for temporarily associating calling line marking switches with calling line connecting switches. and switches for temporarily i i wanted line marking m'r heF:

vi sonnet .iiig swirlierb 3. In a telephone system, lines, calling means, calling-line-marl zing-switches for electrically indicating that a line is calling, switches for electrically marking wanted lines. panel-type calling-line-connectingswitches tor connecting to calling lines, panel-type wanted-line-co1mccting-switches tor connecting to wanted lines, a switch conunon to a group of calling line marking switches and adapted to set the calling line connecting switches onto the calling lines ma rkcd by the cailing-line-marking-switches, and a switch common to a group of wanted line marking switches and adapted to set the wanted line connecting switches onto the wanted lines marked bythe wanted line marking switches.

4. In a telephone system, lines, calling means, calling-line-marking-switches for electrically indicating that a line is calling, switches for electrically marking wanted lines, calliiig-line-connecting-switches for connecting to calling lines, wanted-line-com necting-switches for connecting to wanted lines, a switch common to a group of calling line marking switches and adapted to set the calling line connecting switches onto the calling lines marked by the calling-linemarking-switches. a switch common to a group of wanted line marking switches and adapted to set the wanted line connecting switches onto the wanted lines marked by the wanted line marking switches, and interconnecting switches adapted to interconnect the calling line connecting switches and the wanted line connecting switches.

In a telephone system, lines, calling means. calling-line-marking-switches for electrically indicating that a line is calling, switches for electrically marking wanted lines, calliiig-line-connecting-switches for connecting to calling lines, wanted-line-connecting switches for connecting to wanted lines, a switch common to a group of calling line marli'ing switches and adapted to set the calling line connecting switches onto the calling lines marked by the calling-lineniarking-switches. a switch common to a group of wanted line marking switches and adapted to set the wanted line connecting switches onto the wanted lines marked by the wanted line marking switches. and numerical interconnecting switches adapted to interconnect the calling line connecting switches and the wanted line connecting switches.

6. In a telephone system, lines, calling means. calling-line-marking-switches for electrically indicating that a line is calling, switches tor electrically marking wanted lines, calling-line-connectirig-switches for connecting to calling lines, wanted-linetor connecting to want- ,i common to a group ot 1 itehes and niliii ted connecting c ed lines lit) to set the calling line connecting switches onto the calling lines marked by the calling; lineanarkingswitches, a switch common to a group of wanted line marking switches and adapted to sctthc wanted line connect; ing switches onto the wanted lines marked by the wanted line marking switches, and panel-type interconnecting switches adapted to interconnect the calling line connecting switches and the wanted line connecting switches.

7. in a telephone system, lines, calling means, calling-lineanarkingswitches for electrically indicating that a line is calling, switches for electrically marking wanted lines, panel-type cailing-line-connectingswitches for connecting to calling lines, panel-type wanted-line-connecting-switches for connecting to wanted lines, a switch common to a group of calling line marking switches and adapted to set the calling line connecting switches onto the calling lines marked by the callingdinc-inarki rig-switches, a switch (.ODUHG'Q to a group of wanted line n'iarking switches and adapted to set the wanted line connecting switches onto the wanted lines marked by the wanted line marking switches, and panel-type interconnecting switches adapted to interconnect the calling line connecting switches and the wanted line interconnecting switches.

8.111 a telephone system, lines, calling means, calling-linc-inarkingswitchcs for electrically indicating that a line is calling, switches for electrically marking wanted lines, panel-type callinginc-connecting switches for connecting to calling lines, panel-type wanted-line-connccting switches for connecting to wanted lines, a switch connnon to a group of calling line marking switches and adapted to set the calling line connecting switches onto the calling lines marked by the calling-line-niarkingswitches a switch common to a group ct. wanted line marking: switches and adapted to set ihe wanted line connecting); switches onto the wanted lines marked by the wan ted line markingswitches, and numerical paneltypc ii'itercminecting switches adapted to interconnect he calling; line connecting; s and the wanted line interconnect switcliies,

In a; telephone system, lines, calling means, calling ine-inarking-switches for electrically indicating that a line is calling, switches tor electrically n'iarking wanted lines, calling-line-conncctingpswitches tor connecting; to calling lines, wanted-lino connectingswitch s for coi'inectingg to wanted lines, a switch common to a group of calling line in rlcing switches and adapted to ae the calling; line connecting switches onto the calling; lines marked hy the calling-lineinarking switches. a switch common to a group oi. wanted line marking switches and mama's ulapteiil to set the anted line connecting; switches onto the wanted lines marked by the wanted lino marking switches, trunks leading to the wanted line connecting switches, and combined numerical and trunk finding switches adapted to inferconncct calling line connecting switches and trunks.

10. in a telephone system, lines, alliiiig means, calling]ine-inarhino-switches for electrically indicating that a line is callin switches tor electrically marking wanted lines, calling-line-connectingswitches tor connectii'ig; to calling lines, mn1ted-li11econnacting-switches for connccting to want ed lines, a switch common to a group of calling line marking switches and adapted to set the calling line connecting switches onto the calling lines marked by the calling- 1incniai'ltingewitches, aswitch con'nnon to a group of wanted lino marking switches and adapted to set the wanted line connecting switches onto the wanted. lines marked by the wanted line marking switches, trunks leading; to the wanted line connecting switches, and panel-type combined nnnierical and trunk finding switches adapted to interconnect calling line connectin switches and trunks.

11. in a telephone system, lines calling means, callingg-line-inarkirig-switches for electrically indicating that a line is calling, switcljies for electrically marking wanted. lines. noirnnn'iei'ical calling-line-connecting switches for connecting to calling lines, nonnuinerical wanted-iine-connectingswitches for connecting to wanted lines, aswitch common to a group of calling line lnarking switches and adapted to set the calling line connecting switches onto the calling lines marked by the calling-line inarkingswitches, and a sn itch common to a group of wanted line marking switches and adapted to setthe wanted line connecting switches onto the wanted line marked by the wanted line marking switches.

12. in a telephone system, a plurality oi. lines, a group of switching devices operable in ros 'ionse to the initiation oi a call on a line, a second group of switching devices operab e in accordance with the lc i tion of wanted lines, separate switching; deiccs tor establishing conncc ions with calling andv called lines. and switches toininon to said group and other switches cmiunon to said second groups oi devices tor con rolling the operation oi. said switching: devices.

13. In a telephone system, a plurality oi' lines. a group of switching devices, means operable in response to the initiation of a call on a line For actuatin one of said dcviccs to find the calling line, a second group or Witching devices. means o nirahlc in accordance with the designation of wanted lines for operating one of said devices to select contacts representing the wanted line, 

